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We prove infinitely many cases of conjectured sharp upper and lower bounds for the spanning tree entropy of any planar lattice graph. These bounds come from volumes of associated hyperbolic alternating links, right-angled hyperbolic…

Geometric Topology · Mathematics 2025-05-12 Abhijit Champanerkar , Ilya Kofman

In a graph, a spanning tree is said to be a tree t-spanner of the graph if the distance between any two vertices in is at most times their distance in . The tree t-spanner has many applications in networks and distributed environments. In…

Discrete Mathematics · Computer Science 2014-08-12 Sambhu Charan Barman , Sukumar Mondal , Madhumangal Pal

We show that for any fixed dense graph G and bounded-degree tree T on the same number of vertices, a modest random perturbation of G will typically contain a copy of T . This combines the viewpoints of the well-studied problems of embedding…

Combinatorics · Mathematics 2025-05-30 Michael Krivelevich , Matthew Kwan , Benny Sudakov

For a graph $G$, let $\tau(G)$ denote the number of spanning trees. We show that for every fixed $0 < c < 1/4$, the number of distinct values of $\tau(G)$, as $G$ ranges over simple graphs on $n$ vertices, is at least $\exp(c n \log n)$ for…

Combinatorics · Mathematics 2026-05-26 Vishesh Jain

The {\sc Directed Maximum Leaf Out-Branching} problem is to find an out-branching (i.e. a rooted oriented spanning tree) in a given digraph with the maximum number of leaves. In this paper, we obtain two combinatorial results on the number…

Data Structures and Algorithms · Computer Science 2008-03-06 N Alon , F. V. Fomin , G. Gutin , M. Krivelevich , S. Saurabh

We establish tight lower and upper bounds on the number of edges in traceable graphs in several classes of dense graphs. A graph is traceable if it has a Hamiltonian path. We show that the bound is: - quadratic for the class of graphs of…

Combinatorics · Mathematics 2025-09-03 Michal Dvořák , Dušan Knop , Michal Opler , Jan Pokorný , Ondřej Suchý , Krisztina Szilágyi

We study the multicolour discrepancy of spanning trees and Hamilton cycles in graphs. As our main result, we show that under very mild conditions, the $r$-colour spanning-tree discrepancy of a graph $G$ is equal, up to a constant, to the…

Combinatorics · Mathematics 2021-12-30 Lior Gishboliner , Michael Krivelevich , Peleg Michaeli

A tree with at most $k$ leaves is called a $k$-ended tree. A spanning 2-ended tree is a Hamilton path. A Hamilton cycle can be considered as a spanning 1-ended tree. The earliest result concerning spanning trees with few leaves states that…

Combinatorics · Mathematics 2014-09-09 Zh. G. Nikoghosyan

We prove crossing number inequalities for geometric graphs whose vertex sets are taken from a d-dimensional grid of volume N and give applications of these inequalities to counting the number of non-crossing geometric graphs that can be…

Combinatorics · Mathematics 2013-01-23 Vida Dujmovic , Pat Morin , Adam Sheffer

Given a group $G$, we define the power graph $\mathcal{P}(G)$ as follows: the vertices are the elements of $G$ and two vertices $x$ and $y$ are joined by an edge if $\langle x\rangle\subseteq \langle y\rangle$ or $\langle y\rangle\subseteq…

Group Theory · Mathematics 2017-05-16 A. R. Moghaddamfar , S. Rahbariyan , S. Navid Salehy , S. Nima Salehy

For a set $P$ of $n$ points in the plane in general position, a non-crossing spanning tree is a spanning tree of the points where every edge is a straight-line segment between a pair of points and no two edges intersect except at a common…

We generalize the definition and enumeration of spanning trees from the setting of graphs to that of arbitrary-dimensional simplicial complexes $\Delta$, extending an idea due to G. Kalai. We prove a simplicial version of the Matrix-Tree…

Combinatorics · Mathematics 2011-10-05 Art M. Duval , Caroline J. Klivans , Jeremy L. Martin

We tackle the problem of constructing increasing-chord graphs spanning point sets. We prove that, for every point set P with n points, there exists an increasing-chord planar graph with O(n) Steiner points spanning P. Further, we prove…

Computational Geometry · Computer Science 2014-08-13 Hooman Reisi Dehkordi , Fabrizio Frati , Joachim Gudmundsson

We prove that any graph $G$ with $n$ points has a distribution $\mathcal{T}$ over spanning trees such that for any edge $(u,v)$ the expected stretch $E_{T \sim \mathcal{T}}[d_T(u,v)/d_G(u,v)]$ is bounded by $\tilde{O}(\log n)$. Our result…

Data Structures and Algorithms · Computer Science 2008-08-15 Ittai Abraham , Yair Bartal , Ofer Neiman

We describe the structure of those graphs that have largest spectral radius in the class of all connected graphs with a given degree sequence. We show that in such a graph the degree sequence is non-increasing with respect to an ordering of…

Combinatorics · Mathematics 2008-10-07 Tuerker Biyikoglu , Josef Leydold

We prove Ehrenborg's conjecture that every connected bipartite graph $G$ with parts of size $m$ and $n$ has at most $\frac{1}{mn}\prod_{v\in V(G)} \operatorname{deg}(v)$ spanning trees, and that equality holds if and only if $G$ is a…

Combinatorics · Mathematics 2026-03-19 Boon Suan Ho

One theorem of Nemhauser and Trotter ensures that, under certain conditions, a stable set of a graph G can be enlarged to a maximum stable set of this graph. For example, any stable set consisting of only simplicial vertices is contained in…

Combinatorics · Mathematics 2007-05-23 Vadim E. Levit , Eugen Mandrescu

Spanning trees are relevant to various aspects of networks. Generally, the number of spanning trees in a network can be obtained by computing a related determinant of the Laplacian matrix of the network. However, for a large generic…

Statistical Mechanics · Physics 2011-11-18 Yuan Lin , Bin Wu , Zhongzhi Zhang , Guanrong Chen

Extremal problems related to the enumeration of graph substructures, such as independent sets, matchings, and induced matchings, have become a prominent area of research with the advancement of graph theory. A subset of vertices is called a…

Combinatorics · Mathematics 2024-12-24 Bo-Jun Yuan , Ni Yang , Hong-Yan Ge , Shi-Cai Gong

We consider two notions describing how one finite graph may be larger than another. Using them, we prove several theorems for such pairs that compare the number of spanning trees, the return probabilities of random walks, and the number of…

Combinatorics · Mathematics 2018-09-10 Russell Lyons